Method and apparatus for testing optical devices

Abstract

An output optical receiver is equipped with an array of multimode optical fibers. Each multimode fiber has a core size or core diameter that is much larger than the width of the output ports of the waveguide device. The multimode fibers are spaced apart such that each fiber only receives light from one output port. Each multimode fiber is coupled to an optical power meter. The optical power meter measures the intensity of the optical signal received by the multimode fiber. The optical signal can be provided by a broadband optical signal source or wavelength tunable laser coupled to an input fiber aligned to the input port of the waveguide device. The output optical receiver is also equipped with a cross hair sight and camera to assist in aligning the receiver with the waveguide device.

We claim:  
     
         1 . A method of testing an optical device having an input port and an output port interconnected by an optical path within the device, the device to be tested by passing optical test signals through the device via said path, the method comprising the steps of: 
 (i) aligning with said output port a reception port having an effective cross sectional size significantly greater than the cross sectional size of the output port such that at least a substantial portion of light leaving said output port will be received by the reception port and conveyed to measuring means connected thereto;    (ii) positioning input optical means adjacent to said input port;    (iii) transmitting an optical signal from said input optical means into said input port;    (iv) measuring the signal strength of the corresponding optical signal received by said reception port; and    (v) adjusting the positioning of the input optical means relative to the input port so as to maximize the measured signal strength.    
     
     
         2 . A method according to  claim 1 , wherein the reception port is mounted upon a support in fixed relationship to a sight having a datum spaced from an optical centre of the reception port by a predetermined distance, and the step of aligning the reception port with the output port comprises the step of aligning the datum with the centre of the output port and then translating the optical receiver means and the optical device one relative to the other by said predetermined distance to bring said reception port into alignment with said output port.  
     
     
         3 . A method according to  claim 1 , wherein the reception port is mounted upon a support in fixed relationship to a sight having a datum spaced from an optical centre of the reception port by a predetermined distance and the optical device has a fiducial mark spaced from the centre of the output port by a distance corresponding to said predetermined distance, and the step of aligning the reception port with the output port comprises aligning the datum with the fiducial mark.  
     
     
         4 . A method according to  claim 1 , wherein the optical device has a plurality of said output ports each connected to said input port by an optical path within the device, and a corresponding plurality of reception ports, each having a cross sectional size significantly larger than the cross sectional size of the corresponding one of the output ports, are positioned in registration with the output ports so as to receive corresponding portions of said optical signal supplied to the input port, the signal strength of at least some of the optical signal portions being measured and maximized by adjusting the positioning of the input optical means.  
     
     
         5 . A method according to  claim 4 , wherein the reception ports are spaced apart at pitch intervals corresponding to pitch intervals between the output ports, and only one of the reception ports is manually aligned with the corresponding one of the output ports.  
     
     
         6 . A method according to  claim 5 , wherein the optical device has a fiducial mark at a predetermined distance from the middle of said one of the output ports and the reception ports are mounted upon a support in fixed relationship to a sight having a datum spaced from the middle of said one of the reception ports by a distance corresponding to said predetermined distance, and the step of aligning said one of the reception ports with the corresponding one of the output ports comprises aligning the datum with the fiduciary mark.  
     
     
         7 . A method of testing a plurality of optical devices fabricated on a common substrate, each optical device having an input port and a plurality of output ports each connected to the input port by a corresponding optical path, each device to be tested by passing optical test signals through the device via said paths, the method comprising the steps of: 
 (i) for a first of the optical devices, aligning with said output port a reception port having an effective cross sectional size significantly greater than the cross sectional size of the output port such that a substantial portion of light leaving said output port will be received by the reception port;    (ii) positioning input optical means adjacent to said input port;    (iii) transmitting an optical signal from said input optical means via said input port and path and measuring the signal strength of the corresponding optical signal received by said reception port;    (iv) adjusting the positioning of the input optical means relative to the input port so as to maximize the measured signal strength;    (v) testing the first optical device by passing said optical test signals through the device, via the input optical means, and performing test measurements upon the corresponding optical test signals received by the reception ports;    (vi) indexing the substrate to position each of the remaining optical devices in turn between the input optical means and reception ports, and    (vii) repeating steps (i) through (v) for each of the remaining optical devices.    
     
     
         8 . Apparatus for testing an optical device having an input port and an output port interconnected by an optical path within the device, the device to be tested by passing optical test signals through the device via said path, the apparatus comprising: 
 first support means for supporting said optical device;    second support means for positioning adjacent to said input port of said supported optical device input optical means for transmitting an optical signal into said input port;    third support means for supporting a reception port in alignment with a said output port of said optical device supported by the first support means, the reception port having an effective cross sectional size significantly greater than the cross sectional size of the output port such that at least a substantial portion of light leaving said output port will be received by the reception port;    measuring means coupled to the reception port for measuring the signal strength of a corresponding optical signal received by said reception port; and    means for adjusting the positioning of the input optical means relative to the input port.    
     
     
         9 . Apparatus according to  claim 8 , further comprising a sight mounted upon said third support means in fixed relationship to the reception port, the sight having a datum spaced from an optical centre of the reception port by a predetermined distance, and translation means for effecting relative movement between the reception port and the first support means, following alignment of the datum with said output port, by a distance corresponding to said predetermined distance.  
     
     
         10 . Apparatus according to  claim 8 , further comprising a sight mounted upon said third support means in fixed relationship to the reception port, the sight having a datum spaced from an optical centre of the reception port by a predetermined distance, the optical device having a fiducial mark spaced from the output port by a distance corresponding to said predetermined distance, such that, when the datum is aligned with the fiducial mark, the reception port will be aligned with the output port.  
     
     
         11 . Apparatus for testing an optical device having an input port and a plurality of output ports each coupled to the input port by a respective one of a plurality of optical paths within the device, the apparatus comprising: 
 a plurality of reception ports each for receiving an optical signal from a respective one of the plurality of output ports, each reception port having a cross sectional size significantly larger than a cross sectional size of a corresponding one of the plurality of output ports;    optical signal measuring means coupled to the reception ports to receive optical signals therefrom; and    alignment means for registering the plurality of reception ports with the plurality of output ports, respectively;    the arrangement being such that, when the plurality of reception ports are each aligned with the corresponding one of the output ports, each of the reception ports will receive at least a substantial portion of the optical signal from the corresponding one of the output ports, and substantially none of the optical signals from other output ports.    
     
     
         12 . Apparatus according to  claim 11 , wherein the reception ports are spaced apart at pitch intervals corresponding to pitch intervals at which the output ports are spaced apart, so that, when one of the reception ports is aligned with a corresponding one of the output ports, each of the remaining reception ports is aligned with the corresponding one of the output ports.  
     
     
         13 . Apparatus according to  claim 11 , wherein each reception port is an end of a multimode optical fiber.  
     
     
         14 . Apparatus according to  claim 11 , wherein the optical signal measuring means comprises a plurality of optical power meters each coupled to a respective one of the plurality of reception ports.  
     
     
         15 . Apparatus according to  claim 11 , wherein each reception port has a cross sectional size larger than a cross sectional size of the corresponding output port by approximately ten times or more.  
     
     
         16 . Apparatus according to  claim 9 , wherein the sight includes a video camera for providing a view of the output port and the datum.  
     
     
         17 . Apparatus according to  claim 10 , wherein the sight includes a video camera for providing a view of the datum and the fiduciary mark.  
     
     
         18 . Apparatus for testing an optical device having at least one input port and a plurality of output ports, the apparatus comprising: 
 an optical signal source;    an input optical device coupled to the optical signal source;    an adjustable platform for adjusting a relative displacement between the input optical device and the optical device being tested;    an output optical device having a plurality of reception ports and alignment means for aligning each of the reception ports with a respective one of the output ports of the optical device being tested; and    a plurality of optical signal measurement means, each optical signal measurement means being coupled to a respective one of the reception ports of the output optical device,    wherein 
 the adjustable platform is adjustable to align the input optical device with one of the at least one input ports;  
 the alignment means is arranged to align the output optical device with one of the reception ports, so that other reception ports will be aligned with a corresponding one of the plurality of output ports; and  
 the input optical device supplies an optical signal to the output optical device and to the optical device being tested such that a signal strength of the optical signal received by at least one of the multiple optical signal receivers is measured by at least one of the optical signal measurement means.  
   
     
     
         19 . Apparatus according to  claim 18 , wherein the input optical device is a single mode optical fiber.  
     
     
         20 . Apparatus according to  claim 18 , wherein each optical signal receiver is a multimode optical fiber.  
     
     
         21 . Apparatus according to  claim 18 , further comprising a sight movable with the output optical device, the sight having a datum spaced from an optical centre of a reference one of the reception ports by a predetermined distance, and translation means for effecting relative movement between the reception ports and the optical device, following alignment of the datum with said output port, by a distance corresponding to said predetermined distance.  
     
     
         22 . Apparatus according to  claim 18 , further comprising a sight movable with the output optical device, the sight having a datum spaced from an optical centre of a reference one of the reception ports by a predetermined distance, the optical device having a fiducial mark spaced from the output port by a distance corresponding to said predetermined distance, such that, when the datum is aligned with the fiducial mark, the reception port will be aligned with the output port.